Bluetooth uses a method called bonding for recognising specific devices and thus enable control over which devices are allowed to connect to a given Bluetooth device and for allowing Bluetooth devices to be able to establish a connection without user intervention. A bond is created through a process called pairing. The pairing process is typically triggered by a specific request to create a bond from a user via a user interface.
Pairing typically involves some level of user interaction; this user interaction is the basis for confirming the identity of the devices. Once pairing successfully completes, a bond will have been formed between the two devices, enabling those two devices to connect to each other in the future without requiring the pairing process in order to confirm the identity of the devices. When desired, the bonding relationship can later be removed by the user.
During the pairing process, the two devices involved establish a relationship by creating a shared secret known as a link key. If a link key is stored by both devices they are said to be paired or bonded. A device that wants to communicate only with a bonded device can cryptographically authenticate the identity of the other device, and so be sure that it is the same device it previously paired with. Once a link key has been generated, an authenticated Asynchronous Connection-Less (ACL) link between the devices may be encrypted so that the data that they exchange over the airwaves is protected against eavesdropping.
Link keys can be deleted at any time by either device. If done by either device this will implicitly remove the bonding between the devices; so it is possible for one of the devices to have a link key stored but not be aware that it is no longer bonded to the device associated with the given link key.
(Note: The above description of the Bluetooth pairing process was adapted from an article on Wikipedia and underlies the same license conditions as the original article text.
Original article URL: http://en.wikipedia.org/wiki/Bluetooth
License URL: http://creativecommons.org/licenses/by-sa/3.0/)
Mobile Bluetooth devices such as smartphones, hearing devices, hearing aids or hearing-aid streamers (gateway devices for relaying audio signals between a hearing aid and an arbitrary source, for example disclosed in EP 1 981 253 A1) as well as Bluetooth terminals such as landline phone adapters or TV adapters are known from the prior art. Prior to establishing a secured communication connection between—for example—a hearing aid and a landline phone adapter, the devices require to be paired as described above.
US 2009/0073950 A1 discloses a Bluetooth-compatible headset that can pair up to at least seven wireless communication-enabled devices at once, two of which can be active simultaneously. The headset will automatically switch between two connected devices based on which device has requested an active audio channel. To disconnect the headset from a current audio-gateway device, the headset is either powered off or the pairing memory is cleared. When powered on, the headset will automatically reconnect to the last connected phone.
The disclosed automatic switching between connected devices may not always provide the connection the user desires, and if the user of the headset wants to switch to another device, the user is required to interact manually with the headset.
It is an object of the invention to provide an alternative Bluetooth device for engaging in a wireless Bluetooth connection and a corresponding method and computer program for operating a mobile Bluetooth device.